Conjunctival ultraviolet autofluorescence as a biomarker of outdoor exposure in myopia: a systematic review and meta-analysis.

Outdoor exposure is considered the primary modifiable risk factor in preventing the development of myopia. This effect is thought to be attributed to the light-induced synthesis and release of dopamine in the retina. However, until recent years, there was no objective quantifiable method available to measure the association between time spent outdoors and myopia. It is only recently that the conjunctival ultraviolet autofluorescence (CUVAF) area, serving as a biomarker for sun exposure, has begun to be utilized in numerous studies. To provide a comprehensive summary of the relevant evidence pertaining to the association between the CUVAF area and myopia across different geographic regions and age groups, a systematic review and meta-analysis were conducted. The search encompassed multiple databases, including MEDLINE, SCIENCE DIRECT, GOOGLE SCHOLAR, WEB OF SCIENCE, and SCOPUS, and utilized specific search terms such as "conjunctival ultraviolet autofluorescence", "CUVAF", "UVAF", "objective marker of ocular sun exposure", "myopia", "degenerative myopia", and "high myopia". The bibliographic research included papers published between the years 2006 and 2022. A total of 4051 records were initially identified, and after duplicates were removed, 49 articles underwent full-text review. Nine articles were included in the systematic review. These studies covered myopia and outdoor exposure across different regions (Australia, Europe and India) with a total population of 3615 individuals. They found that myopes generally had smaller CUVAF areas compared to non-myopes. The meta-analysis confirmed this, revealing statistically smaller CUVAF areas in myopic patients, with a mean difference of - 3.30 mm2 (95% CI - 5.53; - 1.06). Additionally, some studies showed a positive correlation between more outdoor exposure and larger CUVAF areas. In terms of outdoor exposure time, myopic patients reported less time outdoors than non-myopic individuals, with a mean difference of - 3.38 h/week (95% CI - 4.66; - 2.09). Overall, these findings highlight the connection between outdoor exposure, CUVAF area and myopia, with regional variations playing a significant role. The results of this meta-analysis validate CUVAF as a quantitative method to objectively measure outdoor exposure in relation with myopia development.

Efecto del suero autólogo en la reparación de la superficie ocular asociada a ojo seco / Effect of autologous serum in the repair of the ocular surface associated with dry eye

l daño de la superficie ocular asociado a la alteración de la película lagrimal causa múltiples síntomas y como tratamiento se usa el suero autólogo. Objetivos: comparar el efecto del suero autólogo sobre la reparación de la superficie ocular, preparado con dos concentraciones diferentes (80 y 20 %). Materiales y métodos: se realizó un estudio prospectivo cuasiexperimental en 25 pacientes diagnosticados con ojo seco, mediante el test de Schirmer, tbut y tinción con rosa de Bengala. Se administró colirio de suero autólogo al 80 % en el ojo derecho y al 20 % en el ojo izquierdo, y después de 30 días de utilización se realizaron nuevamente los tests. Para la preparación del suero autólogo se realizaron los procedimientos éticos y se siguió con el protocolo estandarizado de la Universidad de Lübeck, Alemania, de acuerdo con la guía Bundesãrztekammer y del Instituto Paul Ehrlich. Resultados: la aplicación de suero autólogo al 80 % y al 20 % presenta un aumentoignificativo tanto en el volumen lagrimal (Schirmer) ccomo en la estabilidad y calidad lagrimal (tbut) y se logra, además, reparación sobre la superficie ocular. No se encontraron diferencias significativas con las dos concentraciones, pero con mayores concentraciones se logra un mayor efecto sobre la producción y tiempo de ruptura de la película lagrimal (p<0,080). Conclusiones: la administración de suero autólogo como tratamiento para el ojo seco presenta reparación sobre la superficie ocular en concentraciones tanto del 20 % como del 80 %.

The ocular surface damage associated with the alteration of the tear film causes multiple symptoms, and autologous serum is used as treatment. Objectives: To compare the effect of autologous serum on the ocular surface repair, prepared with two different concentrations (80 y 20 %). Materials and methods: A quasi-experimental prospective study was carried out in 25 patients diagnosed with dry eye through the Schirmer test, tbut and Rose Bengal staining. Autologous serum eye drops were administered to 80% in the right eye and 20% in the left eye, and after 30 days of application, tests were once again performed. For the preparation of autologous serum, ethical procedures were performed and the standardized protocol at the University of Lübeck, Germany, was followed according to the Bundesãrztekammer guide and the Paul Ehrlich Institute. Results: The application of autologous serum to 80% and 20% showed a significant increase in both tear volume (Schirmer) and tear stability and quality (tbut) and, additionally, ocular surface repair is achieved. No significant differences were found with the two concentrations but with higher concentrations a greater effect on production and time of rupture of the tear film is achieved (p<0.080). Conclusions: The administration of autologous serum as a treatment for dry eye presents repair on the ocular surface in both concentrations of 80% and 20%.